Nadi, Muhammad Rizki Gorbyandi
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Surface Evaluation of Tricalcium Phosphate Bioceramic Coating on SS-316L by Electrophoretic Deposition Hermana, Gita Novian; Nugraha, Dhion Khairul; Nadi, Muhammad Rizki Gorbyandi; Sektiono, Moch. Wisnu Arif; Mayello, Randy Mediawan; Farhan, Miftah; Kusuma, Nirmala Cahya; Alfayed, Naufal Alden; Rizqi, Fauzi Muhamad
Jurnal Bahan Alam Terbarukan Vol 13, No 1 (2024): June 2024 [Nationally Accredited Sinta 2]
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jbat.v13i1.49639

Abstract

The development of orthopedic implant materials has become an important topic of discussion lately. The SS-316L alloy is widely used as an implant material due to its relatively low cost, corrosion resistance, and ease of production. However, metal alloys, especially SS-316L, are prone to ion release into the blood over time. Therefore, TCP or tricalcium phosphate [Ca3(PO4)2] is needed to coat the surface of SS-316L, preventing ion release into the blood and enhancing the biocompatibility of the implant material. In this study, TCP coating was applied to the SS-316L substrate using the electrophoretic deposition technique. The influence of deposition time on changes in microstructure and mechanical properties is the main focus of this study. The results of the coating technique indicate that the deposition yield increases with the deposition time. Morphological testing results show that increasing deposition time improves coating quality by increasing the thickness of the coating layer and preventing layer peeling. The coating process also reveals the accumulation of layers in certain areas and the formation of thin layers in other regions. A deposition time of 30 minutes results in a coating thickness ranging from 48.7 to 57.9 µm. Hardness testing, conducted with indentation loads of 50, 100, and 300 gf, indicates that longer deposition times and higher indentation loads during hardness testing result in reduced material hardness.
Investigation of Failure Mechanisms in the U-Bend Tubes of Shell and Tube Heat Exchangers Achyarsyah, Mochamad; Hanaldi, Kus; Purwadi, Wiwik; Hermana, Gita Novian; Siswanto, Ari; Ruskandi, Cecep; Nadi, Muhammad Rizki Gorbyandi
Metalurgi Vol 39, No 3 (2024): Metalurgi Vol. 39 No. 3 2024
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2024.775

Abstract

The U-bend tubes of a shell-and-tube heat exchanger made of SA-234 Grade WPB carbon steel failed prematurely within 14 days after replacement and welding. This study investigates failure mechanisms through an integrated failure analysis that includes visual inspection, dye penetrant testing, chemical composition analysis, hardness measurements, and microstructural characterization. The results reveal that the tube contained 0.324 wt.% C, exceeding the maximum limit specified by the standard, which promoted the formation of Widmanstätten ferrite and reduced toughness. The welded joint exhibited multiple defects, including porosity and lack of fusion, which acted as stress concentration sites. Hardness measurements showed average values of 205 HV in the weld metal, 199 HV in the HAZ (heat-affected zone), and 184 HV in the base metal. Under operating conditions of 275 °C and 58.48 barg, these defects progressively opened, leading to fluid leakage. The escaping high-pressure fluid accelerated erosion-corrosion, as evidenced by oxygen-rich corrosion products detected by EDS analysis. The findings demonstrate that the combined effects of material non-compliance, poor welding quality, and unfavorable microstructural evolution governed the premature failure. This study provides quantitative insights to improve welding practices and material selection, thereby enhancing the reliability of U-bend tubes in shell-and-tube heat exchangers.